(a) Technical Field
The present disclosure relates to a method for controlling a cooling system for cooling a power converter of a hybrid electric vehicle. More particularly, it relates to a method for controlling a cooling system for cooling a power converter of a hybrid electric vehicle by estimating the temperature of the power converter based on its state in the event of a controller area network (CAN) communication error in the power converter.
(b) Background Art
A hybrid vehicle is driven by an internal combustion engine and an electric motor thereby reducing exhaust gas and improving overall fuel efficiency.
A powertrain system of a parallel type hybrid electric vehicle is described with reference to FIG. 4.
An engine 10, a motor 12, and an automatic transmission 14 are directly connected to a drive shaft 16, a clutch 18 is disposed between the engine 10 and the motor 12, and a high voltage battery 20 capable of being charged and discharged by a battery controller 22 is connected to the motor 12 through an inverter 24.
Also, a 12 V auxiliary battery 26 is connected to a connecting line between the battery 20 and the inverter 24 through a DC-DC converter 28 (hereinafter referred to as “LDC”).
Further, a cooling system 30 (e.g., cooling fan or water pump) and a cooling system controller 32 are provided to cool the inverter 24 and the LDC 28 which constitute a hybrid power converter.
Here, the battery controller 22, the inverter 24, the LDC 28, and the cooling system controller 32 are connected to each other through a controller area network (CAN) communication line 36 for signal interface.
Therefore, the battery controller 22, the inverter 24, the LDC 28, and the cooling system controller 32 can transmit and receive information to and from each other through the CAN communication. As shown in the flowchart of FIG. 2, the cooling system controller 32 receives temperature information of each hybrid system through the CAN communication and controls the operation of the cooling system 30 based on the information.
As such, instead of an alternator, the LDC 28 for charging the 12 V auxiliary battery and controlling the power supply to an electronic circuit and the inverter 24 for controlling the motor for driving the vehicle are provided in the hybrid electric vehicle. The LDC 28 and the inverter 24, i.e., the hybrid power converter, include a temperature sensor (not shown) for measuring the internal temperature. The measured temperature data is transmitted to the cooling system controller 32 for controlling the cooling system 30 through the CAN communication.
In a normal state, the hybrid power converter transmits the information of the temperature sensor to the cooling system controller through the CAN communication, and the cooling system controller controls the cooling system by determining the cooling rate based on the received temperature of each power converter.
However, in the event of a CAN communication error in the power converter, the temperature information detected by the temperature sensor in the power converter cannot be transmitted through the CAN communication line, and thereby the cooling system controller cannot receive the temperature information. As a result, it is impossible to provide an over-temperature protection of the power converter.
That is, the cooling system controller for controlling the cooling system sets the operation of the cooling system at the maximum to prevent the power converter from overheating in the event of a CAN communication error. However, such a strategy is problematic since it significantly increases the operating noise of the cooling system and causes unnecessary power consumption of the cooling system.
In other words, in the event of a CAN communication error in the hybrid power converter, the cooling system controller controls the cooling system (e.g., cooling fan or water pump) at the maximum capacity to allow the cooling system to cool the power converter regardless of the actual temperature of each power converter. This cooling logic causes excessive noise in the cooling system and reduces the durability and efficiency of the cooling system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.